Nucleocytoplasmic Shuttling of Influenza A Virus Proteins

Influenza viruses transcribe and replicate their genomes in the nuclei of infected host cells. The viral ribonucleoprotein (vRNP) complex of influenza virus is the essential genetic unit of the virus. The viral proteins play important roles in multiple processes, including virus structural maintenance, mediating nucleocytoplasmic shuttling of the vRNP complex, virus particle assembly, and budding. Nucleocytoplasmic shuttling of viral proteins occurs throughout the entire virus life cycle. This review mainly focuses on matrix protein (M1), nucleoprotein (NP), nonstructural protein (NS1), and nuclear export protein (NEP), summarizing the mechanisms of their nucleocytoplasmic shuttling and the regulation of virus replication through their phosphorylation to further understand the regulation of nucleocytoplasmic shuttling in host adaptation of the viruses.     

Reverse Genetics and Artificial Replication Systems of Borna Disease Virus 1

Borna disease virus 1 (BoDV-1) is a neurotropic RNA virus belonging to the family Bornaviridae within the order Mononegavirales. Whereas BoDV-1 causes neurological and behavioral disorders, called Borna disease (BD), in a wide range of mammals, its virulence in humans has been debated for several decades. However, a series of case reports in recent years have established the nature of BoDV-1 as a zoonotic pathogen that causes fatal encephalitis in humans. Although many virological properties of BoDV-1 have been revealed to date, the mechanism by which it causes fatal encephalitis in humans remains unclear. In addition, there are no effective vaccines or antiviral drugs that can be used in clinical practice. A reverse genetics approach to generating replication-competent recombinant viruses from full-length cDNA clones is a powerful tool that can be used to not only understand viral properties but also to develop vaccines and antiviral drugs. The rescue of recombinant BoDV-1 (rBoDV-1) was first reported in 2005. However, due to the slow nature of the replication of this virus, the rescue of high-titer rBoDV-1 required several months, limiting the use of this system. This review summarizes the history of the reverse genetics and artificial replication systems for orthobornaviruses and explores the recent progress in efforts to rescue rBoDV-1.     

Vaccination against Borna Disease: Overview,Vaccine Virus Characterization and Investigation of Live and Inactivated Vaccines

(1) Background: Vaccination of horses and sheep against Borna disease (BD) was common in endemic areas of Germany in the 20th century but was abandoned in the early 1990s. The recent occurrence of fatal cases of human encephalitis due to Borna disease virus 1 (BoDV-1) has rekindled the interest in vaccination. (2) Methods: The full genomes of the BD live vaccine viruses “Dessau” and “Giessen” were sequenced and analyzed for the first time. All vaccination experiments followed a proof-of-concept approach. Dose-titration infection experiments were performed in rabbits, based on both cell culture- and brain-derived viruses at various doses. Inactivated vaccines against BD were produced from concentrated cell culture supernatants and investigated in rabbits and horses. The BoDV-1 live vaccine “Dessau” was administered to horses and antibody profiles were determined. (3) Results: The BD live vaccine viruses “Dessau” and “Giessen” belong to clusters 3 and 4 of BoDV-1. Whereas the “Giessen” virus does not differ substantially from field viruses, the “Dessau” virus shows striking differences in the M gene and the N-terminal part of the G gene. Rabbits infected with high doses of cell-cultured virus developed neutralizing antibodies and were protected from disease, whereas rabbits infected with low doses of cell-cultured virus, or with brain-derived virus did not. Inactivated vaccines were administered to rabbits and horses, following pre-defined vaccination schemes consisting of three vaccine doses of either adjuvanted or nonadjuvanted inactivated virus. Their immunogenicity and protective efficacy were compared to the BD live vaccine “Dessau”. Seventy per cent of horses vaccinated with the BD live vaccine “Dessau” developed neutralizing antibodies after vaccination. (4) Conclusion: Despite a complex evasion of immunological responses by bornaviruses, some vaccination approaches can protect against clinical disease. For optimal effectiveness, vaccines should be administered at high doses, following vaccination schemes consisting of three vaccine doses as basic immunization. Further investigations are necessary in order to investigate and improve protection against infection and to avoid side effects.     

Prominent Efficacy of Amantadine against Human Borna Disease Virus Infection In Vitro and In Vivo. Comment on Fink et al. Amantadine Inhibits SARS-CoV-2 In Vitro. Viruses 2021, 13, 539

Amantadine (1-amino-adamantane) is a versatile antiviral compound which has been licensed for decades against influenza viruses. During the Corona pandemic, its effect to inhibit SARS-CoV-2 in vitro has been investigated. However, an in vivo oral inapplicability was concluded due to ID₅₀ doses exceeding eight times the estimated maximum tolerable plasma levels reached by 600 mg orally daily. In contrast, amantadine has been shown to be extraordinarily efficient against human neurotropic Borna disease virus (BoDV-1), presenting with both anti-depressive and anti-viral efficacy against a placebo, achieved by a well-tolerated low oral daily dose of 200 mg amantadine.     

中国精神病人外周血博尔纳病病毒P24基因片段检测

目的 探讨博尔纳病病毒与人类精神疾病的关系。方法 采用套式逆转录酶聚合酶链反应(nested RT-PCR)结合荧光定量(FQ)PCR检测了31例精神分裂症病人,16例情感障碍病人以及50例健康人外周血单个核细胞(PBMC)中BDV P24基因片段。结果精神分裂症组BDV P24基因片段阳性率为9.7％(3/31);情感障碍组(0/16)和健康组(0/50)均为阴性。精神分裂症组阳性率高于健康组,但差异无显著性意义(P>0.05)。结论 中国的精神病人中存在BDV感染,但BDV感染是否与精神分裂症发病相关有待进一步研究。     

博尔纳病病毒核蛋白转染人少突胶质细胞的蛋白组学研究

目的 研究博尔纳病病毒(Borna disease virus)核蛋白(Nucleoprotein,p40)质粒转染人少突胶质细胞(Oligodendrocyte,OL)后蛋白表达变化。方法 构建BDVp40质粒转染OL细胞的细胞模型和空载体转染细胞模型,分别提取各组细胞蛋白进行双向凝胶电泳和图像分析,用HPLC-Chip/MS纳流液质联用技术进行差异蛋白分析,NCBI数据库搜索鉴定差异蛋白。结果 BDVp40转染后出现蛋白表达差异,与对照组相比有8个蛋白表达上调,4个蛋白表达下调,1个蛋白只在转染后细胞表达而未转染OL细胞组不表达,其中4个蛋白与神经系统疾病相关。结论 BDVp40转染OL细胞后导致相关蛋白表达改变,其中一部分蛋白与神经系统疾病相关。     

博尔纳病毒在宁夏的人和动物感染的检测

目的对临床VE患者以及其本人接触动物的检测,探讨BDV在宁夏地区的感染状况及感染机制,并分析BDV核酸和转化后的氨基酸序列,构建病毒种系发生的来源。方法应用巢式逆转录酶聚合酶链反应结合荧光定量PCR检测患者及其接触的动物的外周血单核细胞的p24和p40基因片段。对检测阳性标本进行连接测序,应用MEGA和DnaSP4.0软件对测序结果同国外的标准株HE80、H1766、strainV等进行核酸和氨基酸序列对比分析,并构建病毒基因的系统发生树。结果在60例VE患者及其接触的710绵羊中,PCR检测发现有3例阳性,阳性检出率5%;9头绵羊阳性,阳性检出率为1.27%。基因聚合分析显示人和动物BDV的核酸序列和编码氨基酸序列与德国马源性的HE80株同源性高达100%,重构基因系统发生树可见宁夏VE患者和牛羊BDV核苷酸序列与国外的标准株形成宁夏-德国-日本的混合支系,同时宁夏绵羊BDV序列也形成了一个独立的支系。结论宁夏地区人和牛羊存在BDV的自然感染,并且人的感染存在动物源性,其传染途径很可能是呼吸道的传播可能引起脑炎的非特异性的临床症状,病毒在种系发生中与德国马源性HE80株有极高的同源性,病毒可能由国外引入本土,不排除病毒株变异的可能,人和绵羊之间存在相互传染的可能。     

抗博尔纳病病毒磷蛋白单克隆抗体的制备及鉴定

目的以重组的博尔纳病病毒(BDV)磷蛋白(p24)为免疫原制备单克隆抗体,并鉴定其特异性。方法以纯化后的重组BDVp24免疫小鼠,将骨髓瘤细胞与其脾细胞进行融合,经ELISA法筛选出分泌抗p24单抗的细胞株,并对其进行克隆与亚克隆培养,将最终获得的其中2株细胞株分别注入小鼠腹腔制备单抗,经亲和纯化法纯化后,采用ELISA法测定效价,利用蛋白免疫印迹和免疫荧光鉴定其特异性。结果建立了2株稳定分泌抗p24单抗的杂交瘤细胞株,抗体亚类均为IgG1型。纯化后的腹水抗p24单抗纯度为98%和93%,ELISA效价在1∶81 000以上,该抗体均能识别重组p24蛋白和BDV感染人类少突胶质细胞(Oligodendroglia cell,OL细胞)所表达的p24蛋白。结论成功制备了灵敏性高、特异性好的抗BDVp24单抗,为博尔纳病病毒诊断方法的研制及感染机理的研讨提供依据。     

Tick-Borne Encephalitis Virus (TBEV) Infection in Two Horses

A final diagnosis in a horse with clinical signs of encephalopathy can be challenging despite the use of extensive diagnostics. Clinical signs are often not pathognomonic and need to be interpreted in combination with (specific) laboratory results and epidemiological data of the geographical region of the origin of the case(s). Here we describe the diagnostic pathway of tick-borne encephalitis virus infection in two horses using established molecular diagnostic methods and a novel in situ hybridization technique to differentiate between regionally important/emerging diseases for central Europe: (i) hepatoencephalopathy, (ii) Borna disease virus, and (iii) West Nile virus infections.     

贵州遵义地区蝙蝠脑组织BDV-P24基因片段的检测

目的了解贵州遵义地区蝙蝠博尔纳病病毒(BDV)感染情况.方法 采用巢式逆转录聚合酶链反应(nRT-PCR)检测82例蝙蝠脑组织BDV-P24基因片段,阳性产物进行基因序列测定,同源性及分子系统树分析.结果 在82例蝙蝠脑组织中检测出7例BDV-RNA P24基因片段阳性,只有5例成功测出BDV-P24基因片段,与标准株马源Strain V相比较同源性高达99%,出现2个位点的一致性沉寂突变(nt1650T~C,nt1740G-T,突变率为0.9%),与H1766比较其同源性达97%,出现5个位点的一致性沉寂改变(nt1599A~G,nt1671T~C,nt1677T~C,nt1695G~A,nt1740G~T,突变率为2.2%),与He/80比较起同源性为96%,出现7个位点的一致性沉寂改变(nt1566 G~A,nt1581C~T,nt1659 T~C,nt1668 A~G,nt1674 T~C,nt1695 G~A,nt1740 G~A,突变率为3.1%).结论 贵州遵义绥阳地区蝙蝠存在BDV感染,与马源Strain V存在高度同源性,人感染BDV可能存在潜在的动物源性.     

牧羊犬外周血和脑组织博尔纳病病毒检测结果的比较

目的检测同一牧羊犬外周血和脑组织博尔纳病病毒(BDV)p24片段,比较两者阳性率的差异。方法采用改进的荧光定量套式RT-PCR,对新疆伊犁地区圈养的100只牧羊犬外周血单核细胞(PBMC)和脑组织(BT)同时进行BDV p24基因片段的检测,并对阳性标本采用GFP-p24、pMD-19扩增后电泳验证,排除质粒污染,并克隆测序,用Fisher精确检验和χ2检验分析两者阳性率的差异。结果牧羊犬外周血单核细胞和脑组织BDV p24检测的阳性率分别为5%和9%;PBMC组和BT组BDV p24检测阳性率差异无统计学意义(P>0.05)。结论BDV在脑内持续感染,但以RT-PCR对外周血单核细胞BDV p24片段的检测有可能替代脑组织BDV检测,作为大规模流行病学调查的手段。     

病毒性脑炎患者血液和脑脊液博尔纳病病毒p24核苷酸片段的检测

目的探讨博尔纳病病毒(Borna disease virus,BDV)与病毒性脑炎(Viral encephalitis,VE)的关系,以及贵州遵义地区是否存在BDV感染。方法采用巢式逆转录荧光定量PCR(FQ-nRT-PCR)检测了32例VE患者和34例对照组(非神经系统疾病外科手术患者)外周血单核细胞(peripheral blood monouclear cells,PBMC)和脑脊液(cerebrospinal fluid,CSF)中的BDV p24基因片段。结果VE患者PBMC和CSF中BDV p24基因片段阳性率均为12.5%。明显高于对照组(0%,Fisher精确概率检验:χ2=4.524,P<0.05);PCR扩增目的基因片段阳性产物测序后,与NCBI网站GenBank提供的BDV标准病毒株V和H1766病毒核苷酸序列比较同源性为95.35%和98.84%,在4个位点出现突变(nt1649T→C,nt1656G→A,nt1670C→T,nt1676C→T),突变率为4.65%;与H1766病毒株亲缘关系最近。结论遵义及其周边地区部分VE患者中存在BDV感染,并可能与病毒性脑炎发病有关。     

Dual Effect of Organogermanium Compound THGP on RIG-I-Mediated Viral Sensing and Viral Replication during Influenza a Virus Infection

The interaction of viral nucleic acid with protein factors is a crucial process for initiating viral polymerase-mediated viral genome replication while activating pattern recognition receptor (PRR)-mediated innate immune responses. It has previously been reported that a hydrolysate of Ge-132, 3-(trihydroxygermyl) propanoic acid (THGP), shows a modulatory effect on microbial infections, inflammation, and immune responses. However, the detailed mechanism by which THGP can modify these processes during viral infections remained unknown. Here, we show that THGP can specifically downregulate type I interferon (IFN) production in response to stimulation with a cytosolic RNA sensor RIG-I ligand 5′-triphosphate RNA (3pRNA) but not double-stranded RNA, DNA, or lipopolysaccharide. Consistently, treatment with THGP resulted in the dose-dependent suppression of type I IFN induction upon infections with influenza virus (IAV) and vesicular stomatitis virus, which are known to be mainly sensed by RIG-I. Mechanistically, THGP directly binds to the 5′-triphosphate moiety of viral RNA and competes with RIG-I-mediated recognition. Furthermore, we found that THGP can directly counteract the replication of IAV but not EMCV (encephalitismyocarditis virus), by inhibiting the interaction of viral polymerase with RNA genome. Finally, IAV RNA levels were significantly reduced in the lung tissues of THGP-treated mice when compared with untreated mice. These results suggest a possible therapeutic implication of THGP and show direct antiviral action, together with the suppressive activity of innate inflammation.     

Comparative Analysis of Tunisian Sheep-like Virus,Bungowannah Virus and Border Disease Virus Infection in the Porcine Host

Apart from the established pestivirus species Pestivirus A to Pestivirus K novel species emerged. Pigs represent not only hosts for porcine pestiviruses, but are also susceptible to bovine viral diarrhea virus, border disease virus (BDV) and other ruminant pestiviruses. The present study focused on the characterization of the ovine Tunisian sheep-like virus (TSV) as well as Bungowannah virus (BuPV) and BDV strain Frijters, which were isolated from pigs. For this purpose, we performed genetic characterization based on complete coding sequences, studies on virus replication in cell culture and in domestic pigs, and cross-neutralization assays using experimentally derived sera. TSV forms a distinct phylogenetic group more closely related to Pestivirus C (classical swine fever virus, CSFV) than to Pestivirus D (BDV). In contrast to BDV and BuPV, TSV replicates by far more efficiently on ovine than on porcine cells. Nevertheless, pigs were susceptible to TSV. As a consequence of close antigenic relatedness of TSV to CSFV, cross-reactivity was detected in CSFV-specific antibody assays. In conclusion, TSV is genetically closely related to CSFV and can replicate in domestic pigs. Due to close antigenic relatedness, field infections of pigs with TSV and other ruminant pestiviruses can interfere with serological diagnosis of classical swine fever.     

Pre-S Proteins in Chronic Hepatitis B Virus Infection: Markers of Active Viral Infection

The role of large (pre-S1) and middle (pre-S2) proteins of HBsAg in hepatitis B virus (HBV) infection is not fully known. Therefore, we studied the expression of pre-S proteins in the liver and serum of 26 patients with chronic HBV infection, using immunoperoxidase staining and enzyme immunoassay. Pre-S1 and pre-S2 proteins were detected in a large number of patients in both liver and serum, irrespective of the disease activity. Serial sections showed that most cells positive for HBsAg were also positive for pre-S proteins. The localization of pre-S2 and HBsAg was similar, with cytoplasmic and membranous stainings of hepatocytes, whereas pre-S1 was expressed exclusively in cytoplasm. Serum levels of HBsAg, pre-S1, and pre-S2 of DNA polymerase-positive cases were significantly higher than those of DNA polymerase-negative cases. Membranous display of pre-S2 on hepatocytes was observed more often in DNA polymerase-positive patients, and their serum pre-S2 levels were significantly higher than those without it. The predominant localization of cytoplasmic HBcAg usually was associated with active, ongoing hepatitis. Its expression and DNA polymerase activity were significantly correlated. These results indicate that pre-S proteins in serum and the membranous display of pre-S2 on hepatocytes of patients with chronic HBV infection refect active viral replication, but their expression does not correlate with disease activity.     

The Autophagy Cargo Receptor SQSTM1 Inhibits Infectious Bursal Disease Virus Infection through Selective Autophagic Degradation of Double-Stranded Viral RNA

Selective autophagy mediates the degradation of cytoplasmic cargos, such as damaged organelles, invading pathogens, and protein aggregates. However, whether it targets double-stranded RNA (dsRNA) of intracellular pathogens is still largely unknown. Here, we show that selective autophagy regulates the degradation of the infectious bursal disease virus (IBDV) dsRNA genome. The amount of dsRNA decreased greatly in cells that overexpressed the autophagy-required protein VPS34 or autophagy cargo receptor SQSTM1, while it increased significantly in SQSTM1 or VPS34 knockout cells or by treating wild-type cells with the autophagy inhibitor chloroquine or wortmannin. Confocal microscopy and structured illumination microscopy showed SQSTM1 colocalized with dsRNA during IBDV infection. A pull-down assay further confirmed the direct binding of SQSTM1 to dsRNA through amino acid sites R139 and K141. Overexpression of SQSTM1 inhibited the replication of IBDV, while knockout of SQSTM1 promoted IBDV replication. Therefore, our findings reveal the role of SQSTM1 in clearing viral dsRNA through selective autophagy, highlighting the antiviral role of autophagy in the removal of the viral genome.     

宁夏地区病毒性脑炎中新发博尔纳病病毒感染的研究

目的 研究宁夏地区新发博尔纳病病毒(BDV)在病毒性脑炎患者中的感染状况,分析病毒株的核酸序列、编码的氨基酸序列和病毒株的系统发生.方法 套式反转录实时荧光定量PCR检测60例病毒性脑炎患者血液标本;并对前期课题组检测的59例病毒性脑炎患者中BDV p24阳性样本和本实验PCR检测阳性标本使用ELISA法检测其对应脑脊液中p40抗体,对阳性标本进行连接测序,应用MEGA和DnaSP4.0软件对测序结果与国外标准株He/80、H1766、strain V等的核酸和氨基酸序列对比分析,构建病毒基因的系统发生树.结果 PCR检测119份血标本,发现有12份标本BDV p24阳性,阳性检出率为10.08%,7份BDV p40检测阳性,阳性率为5.88%;ELISA检测脑脊液核蛋白抗体,有2份阳性,阳性检出率为1.68%.基因聚合分析显示,7份BDV阳性的核酸序列中有6份与德国马源性的He/80株同源性达100%,1份仅有1个碱基发生同义突变;转录后的氨基酸对比分析显示,7份与He/80株完全一致;重构的基因系统发生树中可见宁夏病毒性脑炎患者BDV核苷酸序列与国外标准株形成一个中国(宁夏)-德国-日本的混合支系.结论 宁夏地区病毒性脑炎患者中可能存在BDV感染,其发生可能与动物的密切接触相关,病毒在种系发生中与德国马源性He/80株有极高的同源性,推断病毒有可能从国外传入本土,不排除病毒株变异的可能.